Single solar flare releases destructive equivalent of 100 mn H-bombs

Washington, Dec 16 (IANS) A solar flare can release the destructive equivalent of a 100 million hydrogen bombs, obliterating everything in its neighbourhood, including every single atom, according to scientists.”We’ve detected a stream of perfectly intact hydrogen atoms shooting out of an X-class solar flare,” said Richard Mewaldt of the California Institute of Technology.

“If we can understand how these atoms were produced, we’ll be that much closer to understanding solar flares,” he added.

The event took place on Dec 5, 2006. A large sunspot rounded the sun’s eastern limb and with little warning it exploded. On the “Richter scale” of flares, which ranks X1 as a big event, the blast registered X9, making it one of the strongest flares of the past 30 years.

Such a ferocious blast usually produces a blizzard of high-energy particles dangerous to both satellites and astronauts. An hour later they arrived, but they were not the particles researchers expected.

NASA’s twin Solar Terrestrial Relations Observatory (STEREO) spacecraft made the discovery: “It was a burst of hydrogen atoms,” said Mewaldt. “No other elements were present, not even helium (the sun’s second-most abundant atomic species). Pure hydrogen streamed past the spacecraft for a full 90 minutes.”

Next came 30 minutes of quiet. The burst subsided and STEREO’s particle counters returned to low levels. The event seemed to be over when a second wave of particles enveloped the spacecraft.

These were the “broken atoms” flares are supposed to produce - protons and heavier ions such as helium, oxygen and iron. “Better late than never,” he says.

At first, this unprecedented sequence of events baffled scientists, but now Mewaldt and colleagues believe they’re getting to the bottom of the mystery.

First, how did the hydrogen atoms resist destruction? “They didn’t,” said Mewaldt. “We believe they began their journey to Earth in pieces, as protons and electrons. Before they escaped the sun’s atmosphere, however, some of the protons captured an electron, forming intact hydrogen atoms.”

“The atoms left the sun in a fast, straight shot before they could be broken apart again.” But second, what delayed the ions?

Imagine two runners dashing for the finish line. One (the ion) is forced to run in a zig-zag pattern with zigs and zags as wide as the orbit of Mars. The other (the hydrogen atom) runs in a straight line. Who’s going to win?

“The hydrogen atoms reached Earth almost two hours before the ions,” said Mewaldt. He believes that all strong flares might emit hydrogen bursts, but they simply haven’t been noticed before, said a NASA release.

He’s looking forward to more X-flares now that the two STEREO spacecraft are widely separated on nearly opposite sides of the Sun (In 2006 they were still together near earth).

STEREO-A and B may be able to triangulate future bursts and pinpoint the source of the hydrogen. This would allow the team to test their ideas about the surprising phenomenon.

“All we need now,” he says, “is some solar activity”.

These findings are scheduled for publication in the Astrophysical Journal Letters.